1. Field
The present disclosure relates generally to a method and apparatus for temperature adjusted control of BATFET current sensing, and more particularly to such control of BATFET current sensing in fuel gauging applications.
2. Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
The demand for precise fuel gauges for smart phone batteries continues to increase. Such a fuel gauge in user equipment (UE) can be accomplished via current sensing. Typical current sensing relies on an external precision sensing resistor which has a low Temperature Coefficient (TC). Such precision sensing resistors achieve current sensing by inserting a series resistor in the high current path. The voltage drop on the sense resistor is measured and converted to current information in order to track the battery's capacity. A disadvantage of this method of precision sensing is a non-zero insertion loss, e.g., inserting the sense resistor in the high current path degrades the battery efficiency, which reduces the amount of talk time that can be supported by the battery. The industry strives for zero insertion in order to improve battery efficiency.
Thus, a need exists for a precise fuel gauge that avoids degradation of the battery efficiency.